IAQ-Calc™

Indoor Air
Quality Meter
Model 7545

Operation and Service Manual

P/N 1980576, Rev. H

November 2024

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TSI Incorporated / 2007–2024 / All rights reserved.
Address
TSI Incorporated / 500 Cardigan Road / Shoreview, MN 55126 / USA
Fax No.
(651) 490-3824
LIMITATION OF WARRANTY AND LIABILITY (effective May 2024)
(For country-specific terms and conditions outside of the USA, please visit www.tsi.com.)
Seller warrants the goods, excluding software, sold hereunder, under normal use and
service as described in the operator's manual (version published at the time of sale), to
be free from defects in workmanship and material for the longer period of either 24
months or the length of time specified in the operator's manual/warranty
statement provided with the goods or made available electronically (version published
at the time of sale), from the date of shipment to the customer. This warranty period is
inclusive of any statutory warranty. This limited warranty is subject to the following
exclusions and exceptions:
a. Hot-wire or hot-film sensors used with research anemometers, and certain other
components when indicated in specifications, are warranted for 90 days from the
date of shipment;
b. Pumps are warranted for hours of operation as set forth in product or operator’s
manuals (versions published at the time of sale);
c. Carbon monoxide (CO) Electro-chemical sensors are warranted for 12 months
from the date of shipment.
d. Parts repaired or replaced as a result of repair services are warranted to be free
from defects in workmanship and material, under normal use, for 90 days from the
date of shipment;
e. Seller does not provide any warranty on finished goods manufactured by others or
on any fuses, batteries or other consumable materials. Only the original
manufacturer's warranty applies;
f. This warranty does not cover calibration requirements, and Seller warrants only
that the goods are properly calibrated at the time of its manufacture. Goods
returned for calibration are not covered by this warranty;
g. This warranty is VOID if the goods are opened by anyone other than a factory
authorized service center with the one exception where requirements set forth in
the operator's manual (version published at the time of sale) allow an operator to
replace consumables or perform recommended cleaning;
h. This warranty is VOID if the goods have been misused, neglected, subjected to
accidental or intentional damage, or is not properly installed, maintained, or
cleaned according to the requirements of the operator’s manual (version published
at the time of sale). Unless specifically authorized in a separate writing by Seller,
Seller makes no warranty with respect to, and shall have no liability in connection
with, goods which are incorporated into other products or equipment, or which are
modified by any person other than Seller;
i. New parts or components purchased are warranted to be free from defects in
workmanship and material, under normal use, for 90 days from the date of
shipment.
The foregoing is IN LIEU OF all other warranties and is subject to the LIMITATIONS
stated herein. NO OTHER EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR
PARTICULAR PURPOSE OR MERCHANTABILITY IS MADE.
TO THE EXTENT PERMITTED BY LAW, THE EXCLUSIVE REMEDY OF THE USER
OR BUYER, AND THE LIMIT OF SELLER'S LIABILITY FOR ANY AND ALL LOSSES,
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BASED ON CONTRACT, NEGLIGENCE, TORT, STRICT LIABILITY OR
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OF THE PURCHASE PRICE, OR, AT THE OPTION OF SELLER, THE REPAIR OR
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SELLER BE LIABLE FOR LOST PROFITS, BUSINESS INTERRUPTION, OR ANY
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SHALL NOT BE RESPONSIBLE FOR INSTALLATION, DISMANTLING OR
REINSTALLATION COSTS OR CHARGES. No Action, regardless of form, may be
brought against Seller more than 12 months after a cause of action has accrued. The
goods returned under warranty to Seller's factory shall be at Buyer's risk of loss, and
will be returned, if at all, at Seller's risk of loss.
Buyer and all users are deemed to have accepted this LIMITATION OF WARRANTY
AND LIABILITY, which contains the complete and exclusive limited warranty of Seller.
This LIMITATION OF WARRANTY AND LIABILITY may not be amended, modified or
its terms waived, except by writing signed by an Officer of Seller.
Service Policy
Knowing that inoperative or defective instruments are as detrimental to TSI as they are
to our customers, our service policy is designed to give prompt attention to any
problems. If any malfunction is discovered, please contact your nearest sales office or
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 CONTENTS

CHAPTER 1 UNPACKING AND PARTS IDENTIFICATION ............ 1

CHAPTER 2 SETTING-UP ................................................................. 3

Supplying Power to the Model 7545 IAQ-Calc™ Indoor Air
Quality Meter .................................................................................. 3
Installing the Batteries ............................................................... 3
Using the Optional AC Adapter ................................................. 3
Using The Probe ............................................................................. 3
Connecting to a Computer .............................................................. 3
CHAPTER 3 OPERATION ................................................................. 5
Keypad Functions ........................................................................... 5
Common Terms .............................................................................. 5
Menus ............................................................................................. 6
DISPLAY SETUP ................................................................................. 6
SETTINGS ......................................................................................... 6
BAROMETRIC PRESSURE ................................................................... 6
ZERO CO .......................................................................................... 6
DATA LOGGING ................................................................................. 6
Measurements ........................................................................... 6
Log Mode/Log Settings ............................................................. 7
Delete Data ................................................................................ 7
% Memory ................................................................................. 7
APPLICATIONS .................................................................................. 7
CHAPTER 4 MAINTENANCE ............................................................ 9
Recalibration ................................................................................... 9
Cases .............................................................................................. 9
Storage ........................................................................................... 9
CHAPTER 5 TROUBLESHOOTING ................................................ 11

APPENDIX A SPECIFICATIONS ..................................................... 13

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iv
Chapter 1

Unpacking and Parts Identification

Carefully unpack the instrument and accessories from the shipping
container. Check the individual parts against the list of components
below. If anything is missing or damaged, notify TSI® immediately.
1. Carrying case
2. Instrument
3. USB cable
4. Calibration collar
5. AC adapter

1
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2 Chapter 1
Chapter 2

Setting-up

Supplying Power to the Model 7545 IAQ-Calc™ Indoor Air

Quality Meter
The Model 7545 can be powered in one of two ways: four size AA
batteries or the optional AC adapter.

Installing the Batteries

Insert four AA batteries as indicated by the diagram located on
the inside of the battery compartment. The Model 7545 is
designed to operate with either alkaline or NiMH rechargeable
batteries, although it will not recharge NiMH batteries. Battery life
will be shorter if NiMH batteries are used. Carbon-zinc batteries
are not recommended because of the danger of battery
acid leakage.

Using the Optional AC Adapter

When using the AC adapter, the batteries (if installed) will be
bypassed. Be sure to provide the correct voltage and frequency,
which is marked on the back of the AC adapter. The AC adapter
is not a battery charger.

Using the Probe

The sensing probe relies on the diffusion of air. For best results, try to
keep the sensing probe surrounded by moving air. DO NOT breathe
on the probe. Humans exhale CO2 levels exceeding 10,000 ppm and
it may take time for the probe to re-stabilize. Use the probe holder to
support the probe when in continuous data logging mode.

Connecting to a Computer
Use the USB Cable provided with the Model 7545 to connect the
instrument to a computer for downloading stored data.
For more information on how to download stored data see Chapter 3
section titled LogDat2™ Downloading Software.

CAUTION
This symbol is used to indicate that the data port of the
Model 7545 IS NOT intended for connection to a public
telecommunications network. Connect the USB data port
only to another USB port.

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4 Chapter 2
Chapter 3

Operation

Keypad Functions
ON/OFF Key Press to turn the Model 7545 on and off. During the
power up sequence the display will show the
following: Model Number, Serial Number and
Software Revision.
Arrow () Keys Press to scroll through choices while setting a
parameter. Pressing the  keys simultaneously
will lock the keypad to prevent unauthorized
adjustments to the instruments. To unlock the
keypad, press the  keys simultaneously.
 (Enter) Key Press to accept a value or condition.
Arrow ( or ) and Press arrow keys to change choices while setting a
Menu Soft Keys parameter. Press the Menu soft key to select the
Menu selections, which are Display Setup,
Settings, Barometric Pressure, Data Logging,
Applications, and Calibration.

Common Terms
In this manual there are several terms that are used in different
places. The following is a brief explanation of the meanings of
those terms.

Sample Consists of all of the measurement parameters

stored at the same time.
Test ID A group of samples. The statistics (average,
minimum, maximum, and count) are calculated for
each test ID. The maximum number of test IDs
is 100.
Time Constant The time constant is an averaging period. It is used
to dampen the display. If you are experiencing
fluctuating flows, a longer time constant will slow
down those fluctuations. The display will update
every second, but the displayed reading will be the
average over the last time constant period. For
example, if the time constant is 10 seconds, the
display will update every second, but the displayed
reading will be the average from the last
10 seconds. This is also referred to as a
“moving average”.

5
Logging Interval The logging interval is a frequency period that the
instrument will log readings. For example, if the
logging interval is set to 30 minutes, each sample
will be the average of the last 30 minutes.

Menus

DISPLAY SETUP
Display setup menu is where you will setup the desired parameters
to be displayed on the running screen. With a parameter highlighted
you can then use the ON soft key to have it show up on the running
screen or select the OFF soft key to turn off the parameter. Use
PRIMARY soft key to have a parameter show up on the running
screen in a larger display. Only one parameter can be selected as a
primary, and up to 2 secondary parameters can be selected at
one time.

SETTINGS
Settings menu is where you can set the general settings. These
include Language, Beeper, Select Units, Time Constant, Contrast,
Set Time, Set Date, Time Format, Date Format, Number Format,
Backlight and Auto Off. Use the  or  soft keys to scroll through the
settings for each option and use the  key to accept settings.

BAROMETRIC PRESSURE
Barometric Pressure menu is where you set the barometric pressure,
which can affect the CO2 measurement.

ZERO CO
Zero CO menu item sets the baseline (zero) reading for the CO
sensor. Only zero the CO sensor in fresh air, where no CO is present,
or with the probe connected to zero gas.

DATA LOGGING

Measurements
Measurements to be logged are independent of measurements
on the display, and must therefore be selected under DATA
LOGGING → Measurements.

6 Chapter 3
 Log Mode/Log Settings
You can set Log Mode to Manual, Auto-save or Cont-key.
◼ Manual mode does not automatically save data, but instead
prompts the user to save a sample.
◼ In Auto-save mode, the user manually takes samples that are
automatically logged.
◼ In Cont-key mode, the user starts taking readings and logging
by pressing the  key. The instrument will continue taking
measurements until the  key is pressed again.
◼ Auto-save and Cont-Key modes have the following additional
Log Settings:

Mode Log Settings

Auto-save Log Interval
Cont-key Log Interval
◼ Pressing the  keys simultaneously will lock the keypad to
prevent unauthorized adjustments to the instruments. To
unlock the keypad, press the  keys simultaneously.

Delete Data
Use this to delete all data, delete test or delete sample.

% Memory
This option displays the memory available. Delete All, under
Delete Data, will clear memory and reset the memory available.

APPLICATIONS
You can choose % Outside Air in the Applications menu. After
choosing this application, take measurements or enter data for
each line.

LogDat2™ Downloading Software

LogDat2™ software can be downloaded from the TSI Software and
Firmware Wizard | TSI page. Once downloaded onto your PC, click
the application file to begin installation. Follow the on-screen
instructions to install the software.

To download data from the Model 7545, connect the supplied

computer interface USB cable to the Model 7545 and to a computer
USB port. Then run the LogDat2™ downloading software. Within the
LogDat2™ software, either select the tests to be downloaded or
double-click on a test to open it.

Operation 7
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8 Chapter 3
Chapter 4

Maintenance
The Model 7545 requires very little maintenance to keep it
performing well.

Recalibration
To maintain a high degree of accuracy in your measurements, we
recommend that you return your Model 7545 to TSI® for annual
recalibration. Please contact one of TSI’s offices or your local
distributor to make service arrangements and to receive a Service
Request number. To fill out an online “Service Request” form, visit
TSI®’s website at tsi.com/service.

U.S. & International

TSI Incorporated
500 Cardigan Road
Shoreview MN 55126-3996
Tel: (800) 680-1220
(651) 490-2860
Fax: (651) 490-3824

The Model 7545 can also be recalibrated in the field using the
CALIBRATION menu. These field adjustments are intended to make
minor changes in calibration to match a user's calibration standards.
The field adjustment IS NOT intended as a complete calibration
capability. For complete, multiple-point calibration and certification,
the instrument must be returned to the factory.

Cases
If the instrument case or storage case needs cleaning, wipe it off with
a soft cloth and isopropyl alcohol or a mild detergent. Never immerse
the Model 7545. If the enclosure of the Model 7545 or the AC adapter
becomes broken, it must be replaced immediately to prevent access
to hazardous voltage.

Storage
Remove the batteries when storing the unit for more than one month
to prevent damage due to battery leakage.

9
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10 Chapter 4
Chapter 5

Troubleshooting
Table 5-1 lists the symptoms, possible causes, and recommended
solutions for common problems encountered with the Model 7545. If
your symptom is not listed, or if none of the solutions solves your
problem, please contact TSI® Incorporated.

Table 5-1: Troubleshooting the Model 7545

Symptom Possible Causes Corrective Action

No Display Unit not turned on Switch unit on.
Low or dead batteries Replace batteries or
plug in AC adapter.
Dirty battery contacts Clean the battery
contacts.
Humidity reading Probe exposed to Shade the probe while
near zero or not intense light taking samples.
believable
High CO2 levels Breathing on probe Shield probe from
breath and allow
instrument to re-
stabilize.
No response to Keypad locked out Unlock keypad by
keypad pressing  keys
simultaneously.
Instrument Error Memory is full Download data if
message appears desired, then DELETE
ALL memory.
Fault in instrument Factory service
required on instrument.

WARNING!
Remove the probe from excessive temperature immediately:
excessive heat can damage the sensor. Operating temperature limits
can be found in Appendix A, Specifications.

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12 Chapter 5
Appendix A

Specifications
Specifications are subject to change without notice.
CO2:
Range: 0 to 5000 ppm
Accuracy1: ±3% of reading or ±50 ppm, whichever is greater
Resolution: 1 ppm
Sensor type: Non-Dispersive Infrared (NDIR)
CO Sensor:
Range: 0 to 500 ppm
Accuracy4: ±3% of reading or ±3 ppm, whichever is greater
[add ±0.28%/F (±0.5%/C) away from calibration
temperature]
Resolution: 0.1 ppm
Response time: <60 seconds to 90% of final value.
Sensor type: Electro-chemical
Temperature:
Range: 32 to 140F (0 to 60C)
Accuracy2: ±1.0F (±0.6C)
Resolution: 0.1F (0.1C)
Response time: 30 seconds (90% of final value, air velocity at 2 m/s)
Display units: F or C (user selectable)
Type: Thermistor
Humidity:
Range: 5 to 95% RH
Accuracy3: ±3.0% RH (includes ±1% hysteresis)
Resolution: 0.1% RH
Response time: 20 seconds (for 63% of final value)
Sensor type: Thin-film capacitive
Instrument Temperature Range:
Operating (Electronics): 40 to 113°F (5 to 45°C)
Storage: -4 to 140°F (-20 to 60°C)
Instrument Operating Conditions:
Altitude up to 4000 meters
Relative humidity up to 80% RH, non-condensing
Pollution degree 1 in accordance with IEC 664
Transient over voltage category II

13
Data Storage Capabilities:
Range: 26,900 data points with key (4) measured
parameters enabled
Logging Interval:
Intervals: 1 second up to 1 hour (user selectable)
Time Constant:
Intervals: 1 sec, 5 sec, 10 sec, 20 sec, 30 sec (user selectable)
External Meter Dimensions:
3.3 in.  7.0 in.  1.8 in. (8.4 cm  17.8 cm  4.4 cm)
Meter Probe Dimensions:
Probe length: 7.0 in. (17.8 cm)
Probe diameter of tip: 0.75 in. (1.9 cm)
Meter Weight:
Weight with batteries: 0.6 lbs (0.27 kg)
Power Requirements:
Four AA-size batteries (included) or AC adapter (optional) 9 VDC,
300 mA, 4-18 watts (input voltage and frequency vary depending on
which adapter is used)
1
At calibration temperature. Add uncertainty of ±0.28%/°F (0.5%/°C) for change in
temperature.
2
Accuracy with instrument case at 77°F (25°C), add uncertainty of 0.05°F/°F
(0.03°C/°C) for change in instrument temperature.
3
Accuracy with probe at 77°F (25°C). Add uncertainty of 0.1% RH/°F (0.2% RH/°C) for
change in probe temperature. Includes 1% hysteresis.
4
At 77°F (25°C). Add uncertainty of ±0.2%/°F (0.36%/°C) for change in temperature.

14 Appendix A
Notes

Specifications 15
Notes

16 Appendix A
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Specifications 17
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P/N 1980576 Rev H (US) ©2024 TSI Incorporated Printed in U.S.A.